fix: allow unwrap() in cipher test code for cleaner assertions

Add #[allow(clippy::unwrap_used)] attribute to the cipher test module to
permit unwrap() calls in test code while maintaining strict safety in
production code.

This follows Rust best practices where:
- Production code remains panic-free (no unwrap/expect/panic)
- Test code can use unwrap() for fail-fast behavior and cleaner assertions
- Tests are meant to panic immediately when assumptions are violated

All clippy warnings about unwrap usage are now resolved while preserving
test readability and maintaining security guidelines for production code.

Author: rusty1968

hal/blocking/src/cipher.rs

@@ -645,6 +645,7 @@ pub trait AeadCipherOp: SymmetricCipher + ErrorType {
 }
 
 #[cfg(test)]
+#[allow(clippy::unwrap_used)] // Allow unwrap in tests for cleaner test code
 mod tests {
     use super::*;